Effects of ammonia and nitrite accumulation on the survival and growth performance of white shrimp Litopenaeus vannamei

Ammonia and nitrite levels caused by shrimp excreta and metabolic waste and organic detritus are important limiting factors in intensive aquaculture system, the purpose of this study was to determine how ammonia and nitrite accumulation caused by accumulated these compounds affected survival and growth performance of white shrimp Litopenaeus vannamei. Unconsumed feed, feces and seawater in treatment group were not removed or replaced over a 33-day period, while unconsumed feed and feces in control group were removed with a siphon tube and 60 % seawater was replaced once-daily. Significantly higher ammonia and nitrite concentrations were accumulated in the seawater of treatment group from day 6 to day 33 and from day 9 to day 33, compared with control group, respectively. Significantly lower survival rate, weight gain percentage, length gain percentage and specific growth rate were recorded in treatment shrimp, compared with control shrimp. Significantly higher lipase, superoxide dismutase, and catalase activities, malondialdehyde content, relative expression of 4E-binding protein 1, p70S6 kinase, glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase mRNA were detected in the hepatopancreas of treatment versus control shrimp. Significantly lower protease, glutathione reductase and glutathione peroxidase activities, and glutathione content were detected in the hepatopancreas of treatment versus control shrimp. Meanwhile, hepatopancreas in treatment shrimp showed disorganized tubules, blurred boundaries, decreased or disappeared B, R and E cells, injured connective tissue between liver tubule, infiltrated hemocytes, narrowed lumen, and vacuolization compared with control shrimp. These findings might indicate that ammonia and nitrite accumulation caused by accumulated waste in aquaculture tanks could significantly reduce survival, growth performance of L. vannamei with hepatopancreas damage, which was resulted from accumulated reactive oxygen species. Therefore, ammonia and nitrite accumulation may significantly impact shrimp production in intensive aquaculture system.